Fatherhood
by Aeris Hikari
Summary: Serie of Onshots about Father Figures in Undertale and it's AUs
1. AMBITION

**Undertale was created by Tobyfox. This guy is a genius and i unly use his characters.**

* * *

Her sharp teeth bit into her jaw. The pain seem bearable . It's not the first time, and it will not be the last, she khew it in her bones.

She gave almost all her magic for it, it hurt like hell, but she is in hell. A hell called the Underground. Here, it's Kill of be Killed, and she will not let anything kill her. Human, Monster, nothing!

Her husband is nearby, sharing his magic to give birth to the new soul. He's just here by duty, not by choice. Little bones form in her arms, lifeless, another failure. She says nothing. Her knight went away, decieved. She failled him once again.

She got to her feet, leaving the newborn; she don't have to watch it dust. She'll do better next time,

but when she's about to pass the door, she heard a faint cry. Surprised, she turns around and sees the tiny baby moving, crying. His dark blue soul is pounding in his chest. How can it be?

She watches him closely, One HP...

Too bad, but a last, she didn't fail this time.

Taking the newborn in her arms, she envelopes him in a blanket, thinking. How can a creature so weak could survive in this place. He was just free EXP to the other monsters, and a weakness for her and her husband.

She finds him in Hotland, watching the magma, lost in his thought. The baby is asleep in her arms. She bows before him and present the newborn.

-Mon Seigneur, your Son lived. But i'm afraid he just has One Hit Point.

She caresses the smooth skull of her son. He's beautiful. Just, imperfect; and if there is one thing her husband hate more that humans, it's imperfection; and as she thought, she sees him using his magic, creating a purple sword, aiming at her child.

-Then, I shall end his miserable life before someone else harvest his EXP...

He's not even hesitating. How can he?! Furious, she unleashed her magic, attacking her Knight. He don't stand a chance but her instinct act for her. Only her can have the right of life or death on this baby.

-Don't you dare Gaster!

A wave of yellow magic fly to the knight. He deflect it easely, back at her. She fall on the ground and his shadow come over her and her baby. The child is crying. He's loud. At least, death will shut up this sound. But she's a mother now. And even in this world, a mother can't give up on her future, on her descendant. Her husband is about to kill her and the baby, aiming his sword without a word. But he stop as she speak:

\- He may be free EXP but he's the son of Gaster the Powerful! How do you think everyone will react? Knowing that the Great Knight himself kills babies... His own blood! The Queen herself has forbidden to kill the children. What a reputation you'll have.

She sees him narrow his eyes.

-Killing me or this child won't bring you anything but shame. Now think of this. This weak creature can be a new proof that you're the greatest Knight ever. Imagine. You raising a useless monster with one HP to be one of the most powerful Monster that ever have been. Everyone will think he's a easy kill, but with your training and enough motivation, you can make the whole Underground kneel before your descendant; and you and me will be in the shadow, pulling his strings... What do you think Mon Seigneur?

She waited, looking at the face of ther once loved one. He smile and the sword disapeard before her eyes. He the takes her face in his holed hand and squeeze her bone. It hurt a lot.

\- That's why I married you Lucy... So ambitious... And smart. I love that.

He looks at the baby crying in her arms and takes it with force. He look at him, she's afraid he might let him fall in the magma.

-But I warn you Lucy, if you show weakness again, you'll be dead.

He taunts her, letting the baby fall just to grab it again by the head, above the magma pit.

-BOTH OF YOU...

Years passed, he has grown and now is old enough to use his magic. Mother says that he's still a child but he desagrees. After all, Master already began his training.

He never saw anyone in this dark place except the Master, his mother and the few opponants the Master offered him.

He's hidden, he don't know why. Mother tried to explain to him that he's not ready for the real world. That he must be the fiercest of all and understaind how it works. He likes Mother. she's not yelling at him like Master . He can't see her often. He only can see her if he progresses. So he does his best.

He always does his best. But it's never enough. Never ever. So he's hurt by the Master; he didn't count all the time he almost dusted because of his weakness. A scar on his right eye acts as a reminder of the cruelty of the Master. When he was four, he tried once to call him Father and that simple word triggered a rage in the Master. He remembers what Master told him this day:

-You haven't earned the right to call me that.

He wanted to gain this right. To be praised by his Father, not his Master. Then, he'd be his equal.

He had to learn the lessons of life as the Master told him.

Never ever let anyone hit you.

LOVE must only be a Level of Violence.

Never ever show weakness.

Any weakness can be used against you.

Never Ever show mercy.

It's Kill or be Killed.

Only Mother called him his birth name. His font, as she told him one day. Master called him Boy, or Faliure or Soldier. He's nothing else. But he want to be something more, for the Master.

Today is special. Today, he gained a LV, but his HP is still the same. He loves when he gains HP. Master is nice to him when he does. He don't hit him and even pet his head. He tries not to smile when it happens, he's not allowed to. But for him, it's the best feeling ever. It's almost like if Master loved him.

But this time, he can't see Mother, he don't have a pet. Master wants to show him something.

This something is small, it doesn't look like a soldier like him.

-What is it Master?

He's suspicious, he didn't like that little thing. Do he have to kill it too?

-Let me present to you, Papyrus. Your brother and rival from now.

A brother? He hadn't seen Mother in month and now he had a brother? He looks at him. He's not a good opponent.

-My rival?

-Yes. Look at him. He's perfect. The son I always dreamed of.

Hatred. That's what he felt for the baby at this moment. Why this thing could be the son of Master and not him? Why did he deserve a name by the Master and not him? How could he be so perfect? He looks at his HP and frowns. Papyrus has more HP than him and his ATQ and DEF are higher than his.

-How do you feel Boy?

-Can I dust it Master?

He didn't hesitate one instant, bones are already circling around the crib, the baby tries to grab one as it passes in front of him.

-No.

Master's voice is calm, as always. So he makes the bones disapear.

-Know that it's important to get allies. If you get to gain the loyalty of a stronger monster or one with influence, monsters will respect you. Loyalty is a rare virtue, gaining it is harder than killing some runt. It means that monster is willing to do anything for you, and will always make choices in your favor . Making your life easier. Having a loyal servant is a symbol of your greatness. Now Boy, there are numerous paths you can choose from now.

Master takes the baby in his arms.

-You can consider Papyrus as a threat and wait for the day when I'll let you fight him. You can accept the rivalery expecting to be better than him so I can call you my son. You can also be stupid enough to try and love him as your brother, being weak is what you do best after all. Or...

Master placed the baby in his arms

-You can rase him yourself. Making him the perfect pawn. A puppet for you to play with. Make him love you, do all the things you don't want and inspire respect in his soul. He'll be yours to command. So. What do you wish to do Boy?

He never really had a choice before. It was strange. He looked at the eyes of the baby. He hated that thing with all his soul. He could still drop it on the floor. Babies are fragile and that could kill it, but he thought about what Master says. Having a loyal servant inspired respect.

-How do I take care of him?

He finally asked.

He was his universe. All he wanted to do was to please him. How he loved him, it almost hurt.

He was not suposed to. Master always took him aside to talk to him, saying that love is a weakness, that one day they might fight. But he refuses.

Never will he willingly hurt his brother. The contrary was not true alas, but he knew why; and that made him love him more and more.

All brother wanted was to protect him from the Master. From their father; if Master thought that they hate each other, then he would be safe. But he loves his brother too much and Master know it. He won't let him hurt brother again.

After finding the Master's secret, he used it without him suspecting who did it. What a marvelous power. He didn't like it but as long as his bro was okay, it was worth it; but Master hid it too well now. He's scared. What if it happens again?

-S... Sans?

He asked one day, they were alone in the training room. He could speak freely. Almost...

-Do you know Father have a device to rewind time?

His brother gave him a strange look. He was the taller one but he felt so little when his bro look at him like this.

-Is that one of your stupid jokes Papyrus?

-No, I swear. He uses it when he kill you in training or when... when you kill him.

He saw the sharp teeth of his brother as he smiles at the idea. He is happy to see his brother smile. For so long he didn't even knew how to do that, Master had forbade it. When it was only the two of them, as they grew up, he did all he could to see his brother smile. Especially when he didn't want to.

-I think you took too much hits on your head.

-But it's true! You're so strong now that even he can't beat you! I... I could steal the device and we could dust him and...

-Stop! He's our father! We can't dust him like that!

-He's not our father! A real father wouldn't treat you like that! I've read it in books! Fathers are suposed to protect. All he does is using you to prove a point!

It hurt. Sans hit him hard. He fell on the floor, whimpering. He let his brother attack him. And all he do is ask for mercy. Because he loves his brother. More than his life. And more than his sanity.

His HP is low, so low... He lost a tooth again. He will need time to recover but Sans is calm now.

-Now... what is this device you talk about? You are way too stupid to invent a story like this one.

It's over now. They are free. He told the story to his lord. So he can remember, just a little. He would never hide any information from lord, even as crazy as this. No monster remembers the Great Knight. Only him. And his lord as long as he told him the story of their battle for freedom again and again.

How they fought and how he ended up saving Sans, pushing the Master into the Core.

The lord knew that the only thing keeping him from killing himself was the love they shared. In this world, it's Kill of be Killed. And the only monster they could count on was each other.

He was happy. Really happy. He belongs only to his Lord now, and he will do whatever he have to in order to keep him safe in the Underground. Everyone knew to never underestimate the Great and Fierce Sans and his Lapdog Papyrus, for they were the most powerful duo in all Swapfell.

* * *

 _First Oneshot about the principals AUs._

 _Hope you've liked it._

 _I want to thanks_ _Mysterie1985_ _who helped me, correcting this text. Whithout her, this text would have bee, illisible._

 _And thanks to Petra who asked a simple question about my Comic: Daddy's Secret (on Deviantart). Because that's how i came with the idea._

 _Se you soon for an other AU!_


	2. Weakness

He was angry. Angry against his wife, angry against himself, angry against the king. It was like a fire was burning inside of him. His child, his first born child, after too many attempt, was weak. Before, he wouldn't have mind. He, maybe, would even wanted to show him to the world, proud to be father, proud to have the first skeleton born in the Underground to be his son!  
But now... he was just scared.  
With the latest events, and the new law of the king, the baby in his arms was a real curse. The infant only had one HP one Attack and one Defence. No more. And in this world, it was kill or be killed.  
He knew the baby was in permanent danger. Every monster would see him as free EXP.  
At the beginning, he thought the law was just a phase, that the king would apologise and tell the monsters to calm down and to be pacifist again. But he was wrong. Oh, so wrong.  
The king was so far in his delirium that he made an example of a citizen who mocked the new law. He showed to all the monsters how easy it would be to gather EXP and becoming stronger to fight the humans.  
He tried to talk to the king, to change his mind. Asgore then told him that the only reason he was still alive was because he was to precious for the Underground. Because he created the Core and was the only one who new everything about it. So no one could kill him to take his place or just get EXP... But he was now aware that the mercy never concerned his family.  
And the baby was the biggest weakness he had. Not only he couldn't defend himself, even growing up, with this stats but he loved that little bonehead the instant he saw him.  
He wanted to protect his son more than anything. So he had to make a choice.

* * *

Lucida watches her reflexion in the mirror. Everyday she find new alterations, new details in her feature that frighten her. Today, her cheeks seemed sharper, more angular. She don't like it. If only it was on herself.  
Years had passed since the Law. Kill or be killed. Monsters were adapted to their new life. Now, rare were the monsters who criticise the Law out loud. Ever her husband became quiet about it years ago. And she new it was only to protect his family.  
Both skeletons had gained LV, most of the time defending themselves. Now, even children's gained LV. It was considered bad parenting not helping them to do so.  
Maybe her child was the last one without LV. But his body was changing too. One morning, when she checked on him, she saw his white pupils turned determination red. Hers turned that same color soon after.  
And this morning, when she brought him his breakfast, one of his teeth was gone. Not a baby teeth but a permanent one. And where a hole should have been in his mouth… There was a tooth growing already. But, instead of a regular one, this one seemed really sharp.  
It couldn't be natural. She won't believe it! But she had to wait for her husband to come back.  
She couldn't just call him. Not about Sans. Sans was their treasure. Their hidden treasure. They only could talk about him at home. Face to face. When no one was around.  
Her son was waiting. She knew he was. She had found a new book in the dump today. It would help him out of his boredom. She wished she could do something for him. She wished to let him go out of his room sometimes. But she couldn't lose him. He was too precious, too fragile.  
She stopped looking at her reflexion and headed downstairs, to the basement. Far in the cave she found here was a private lab. And in that private lab was her child's room.

* * *

After the 24601th attempt, he finally done it. He found the code to open the door. He tried every number combination until finding the good one. He was so proud, and he bets his dad would be too if he wasn't so paranoid. It was like if he completed the greatest puzzle. Or at last it was how he saw it in his head.  
Mom and Dad weren't home so he could go and try to do new stuff. And without his parents supervision! That was the best day ever!  
Excited, he ran upstairs, in the living room. He jumped on the couch, tried to find something interesting in every books he could find and tried to get the TV to works.  
He couldn't care less about the time, he was free!  
He was curious about the other rooms in the house… or in the cave, after all, Mom always was proud to say the carved it herself to be like a real house. There was three rooms he has never seen  
The first room was boring, it was a bathroom. And he certainly didn't want to take a bath now. In the second, it as a bedroom. His parent's bedroom. It was a mess! Socks on the floor, cloth on every furnitures, mostly dresses. He couldn't say if it was his dad's or his mom's cloth. But he searched the room to see if there was something interesting.  
He found a big folder in a drawer, all in Wingdings.  
He could stay here and just translate it but he wanted to explore what's behind the last door.  
And he was shocked. Because there was a perfect child room. But for a baby. And full of toys. He heart broke. Was this room for him? He wasn't a baby anymore! The bed was too small for him. It couldn't be for him! Maybe they wanted to get rid of him and have another child! A better one, not a failure.  
A child with normal health, normal attack and that could make his parents proud.  
He couldn't. They said he was different, he had to be hidden, it was for his own good. But he knew.  
The only things you keep secret is your mistakes. He knew that. Because he told everything to his parents, except when he did wrong. He couldn't. Doing wrong ment hurting. And he didn't want to be hurt again.  
He was the biggest mistake of his parents. And he hated himself for that. But what could he do? Dad already tried to fix him but it always end up with hurts, cries or stress. And he gave up trying. Now the only thing Dad did was teaching him about Science.  
He don't know how long he been in this room. Looking, crying, thinking. But his time is done. He hears the keys tuning in the lock. One of his parents is home. He will be punished.  
He wished to be punished for once. Because if they did, it means they still care a little.

* * *

Aging. It was the only thing that betrayed them. He tried to hide it with make up, it worked for a time. And having a second child only accelerated it. Now he needed glasses to read and his coworkers became aware of the changes. They asked him how he've aged so fast with Papyrus being only four. He never answered. He looked at them with annoyance and threat.  
Today, three prisoners dusted because of the experiences. More EXP for him. It became so easy to watch them suffer and die. But every time he had to see Asgore, he tries to reason the old King.  
And he knew Asgore hated him for that. He knew very well the orders Asgore gave to his coworkers. Nova told him.  
At last, he still had a friend.  
He was the only one who never asked acces to the Core blueprints. And even if he had, Gaster would have never give it to him.  
Him being the only one knowing all the Core secrets was one of the reason he was still free and alive. The Levels Of Violence he gained helped him defend his family. Monsters were afraid of the terrible Royal Scientist.  
So afraid that Gaster could let his second born live a normal life. He never hide Papyrus to anyone. The young and healthy baby bone was his pride. And, he had to admit, a way to keep his firstborn safe. Now he had a reason to age. He was a father to the rest of the Underground. No one will search for Sans. And Papyrus was able to defend himself.  
A new day is over, he goes home wanting to see his wife and sons again. To see the love in their eyes. To be away from the horrors of life. Away from the infection Determination.  
He arrives in Waterfall and go for the door of his home. Something is wrong.  
There is dust on the doormat. He enters and see no one.  
"Lucida? Papyrus?"  
He can't call his precious first born. If there is an intruder, he can't let them find Sans.  
With caution, he walks in the living room. On the floor, Dust. And a recognisable thorned dark green dress with a blood red turtleneck. Lucida's favorite cloth…  
Other cloths are on the floor. Big, small… He's scared. What happened? Where was Papyrus? In shock, his eyes goes to the basement door. It's open.  
His phone ring. He don't answer and begin to search for his precious sons. Papyrus room is intact. The private Lab is upside down. His files probably stole. There is traces of fight everywhere. The weapon he worked on had disappeared.  
But the worst was in his son's secret room. On the bed was dried marrow, a note and a single sharped tooth.

* * *

"So you're able to read that?"  
"Yes." was all he answered.  
"And you know all Gaster's secret codes."  
"Yes." he didn't want to answer. All he want is in the other side of the wall.  
"Then, translate this for us. And don't use your weird magic again. Or you know what will happen."  
For the first time he was usefull for someone but… he would have prefer not. Because he was useless for his family. Not even able to stop them. To protect his brother! He tried, he was even able to dust and hurt most of them but it wasn't enough.  
When they found him, they beat him to the brink of dusting and only kept him alive because of his stupid journal. He should have hidden it better. And he should have never wrote it in the first place! Now they knew he read everything his dad wrote even the triple coded document about his most prized secrets.  
They were using him. Because he was exactly what they needed. He was his father's greatest weakness. For everything.  
His bones are still hurting him but he takes the pen Nova gives him and begin to write. He can't disobey. He made the mistake once. And it costed his mom's life.  
He really is useless, he only makes mistakes. He hates himself more than anything.  
Papyrus could have been safe. If it wasn't for him getting mom killed, Papy would have never go out of his hiding place! His Bro is so cool and powerful. Only four and he disted a grown up with a surprise attack. Only to be captured too.  
So he writes. Papyrus's life depend on it.

* * *

It's over. The nightmare is over and he's finally awake. He's still in a cage thou… Why he is still in a cage?  
He calls for his brother.  
Then the door is open and his big brother is here.  
"Why you took so long? I'm hungry!"  
Big Bro enter the cage and takes him in his arms. He's crying.  
"CRYING IS FOR WEAK"  
"Sorry. I'm weak. I'm useless you know that Pap."  
Since when his bro have a scar on his skull? Whatever. He wanted to eat. And why was he in the cage of his nightmare? Maybe it was one of his brother's jokes. He couldn't he still love his big bro.  
"I TEACH YOU TO BE A WEAL MONSTER!"  
His brother cry even more. He have a headache. He can't recall what happen. He want to go home. He want to be in his room with his toys and...  
"BRO? I WANT MOMMY…"  
His bro look broken. He don't work anymore. He look hurt. Yes he was hurt outside, but outside are just bobo. Mommy can make the bobo go. But it's his eyes who hurts.  
Big Bro says nothing, he just cry even more. It's annoying. But for a reason, he begins to cry too. Why is he crying with his brother? Why he wants a hug? Why… Mommy… He can't recall. He want to!  
The nightmare is not over isn't it? It will never be over. He see it in Sans eyes.  
"I WANT TO WAKE UP! I WANT TO GO HOME!" he cries.  
But he can't.  
"Pap... " His brother's voice is broken. He's too soft. Being soft will not scare the nightmare away. "We… can't… Dad… Dad is…"  
"WHO?"

* * *

So here is the second Oneshot of the serie! And it's about my favorite AU.

It wasn't corrected like the last one so if you see errors (and there must be plenny), please comment so i can correct it. Because English is not my native language.

See you next time!


	3. Denial

**Undertale was created by Tobyfox. This guy is a genius and i only use his characters.**

 _3rd Oneshot of my serie about AUs. Now i've made the 3 main AUs._  
 _Once again, i've still not corrected this so if you see any mistake, comment and tell me please._

* * *

It is the best day of his life. He hug his perfect wife and looks at his perfect little bone. Finally he is a dad! He wants to scream to all of the Underground the good news!  
But for now all he wants is to spend time watching over the newborn. He is so cute! He's perfect!  
In his mind, he already is planning the future of the baby. Obviously, he'll be brilliant and strong like his father! He could be the next Great Knight! He'd need training for that. Like always, he start to talk too fast to his sleepy wife. Explaining what he want for their son. Soon she fall asleep and he pick the baby in his arms.  
"Hey! Hello you, it's me! Your papa! You're the cutest thing in the world. I know you have low stats for now but you know what? Forget what the Doctor said. I know that with training and a lot of love, you can improve. You'll be the happiest and greatest monster ever, I promise."

* * *

"Come one Sans! It isn't that hard i know you can do it!"  
Every Time he hears his dad say those words, he feels his soul coming full of joy. He loves the attention. He crave this and everything he want is popularity. He already is the number one in his Dad's heart. Now he must win the rest of the world's love.  
Dad wants him to be the next Great knight. His friends at school told him that the Knights were a thing of the past. Now everyone looked upon the Royal Guard for protection against humans. But he know they're wrong. After all, Dad is the last Knight and the strongest monster ever! With his help, he can go over his little HP problem. He already got his Defence and attack rise up from the training but his HP are still at one point.  
His father encourage him to the newest exercise to try to fix that. After all it can be fix. Dad say it all the time.  
But not Mom. Sometimes, when he's too excited to sleep, he hears them talk. And she's upset, often. He could say all the time. She say that it's never going to fix itself, that only EXP, he wonders what she meant by that, can improve one's HPs. But she's wrong! He know that because Dad always say it.  
Mom said one day that Dad was in denial of the problem. He never knew Dad could be that angry.

* * *

"Put that down! Put that down!"  
He was upset. How Dad dares to hold someone else? A baby Brother? He never wanted that! He wanted his Mom!  
Why Mom wasn't there anymore? Dad told him she was in vacation. He wanted her back! The baby could go on vacation! But not his mom!  
So he cries, he scream, he do everything he know that always makes his parents change their mind. But no. Dad keep the baby in his arms, he cries. Dad never cry.  
What's going one? And the Baby cry too loud, it hurt the skull!  
"Dad put that down now!"  
"It not a That. It's your brother, Papyrus. Your Mother loves him very much, as much as she love you. So please, take care of him while she's away. Can you? She'll be so happy."  
He pouts. He don't like this. Dad get one one knee and show him the baby closer. He still cry too loud.  
"Come one, say Hello."  
He hardly hear his day talk because of the baby. But he want Dad to look at him and to praise him so…  
"HELLO PAPYRUS!" he says with a large smile.

* * *

It's not normal. He don't like it at all. He watches as his brother grow, he's not very tall. In fact, he is too small. Sometimes he read the growth chart for a skeleton in the old books in the library. And Sans is way below average.  
He asked his father once about that. He told him that Sans was a very special and perfect Skeleton. Special, he agreed. His brother was the coolest ever. But perfect… He could write a whole book about why not.  
First, his attitude. Maybe he was only eight but he could see his brother was selfish, childish and full of himself. But he could blame Dad for that. Always praising Sans, never scolding him for his bad behavior and giving him all he wanted.  
His big bro was a spoiled brat… a eighteen year old brat.  
Second, his naïveté. His brother was not stupid, he knew that. But he was too naive for his own good. He still believed in Santa! And himself knew about Santa last year. Dad's told him to not broke his brother dreams. He agreed only because he loved Sans so much.  
And then, there was the HP problem. Skipping some classes, he knew that HPs were importants and only sleeping in a comfortable INN of gaining Levels of Violences could increase one's HP. Still, Dad trained Sans to believe that the problem will go away one day. It couldn't be true. And it was dangerous. What if a human comes by and attacks his big bro? Yes, his defence is high but it was worrying.  
He tried to talk about that to Dad, about his fear to loose his bro but… It ended with more problems.  
Dad broke in front of him, no more in denial and showing him a strange device Gerson made. A device used more than once to keep Sans alive. Now, he checks twice to know what day it is. And when it's the same as Yesterday, he knows his brother was hurt.

* * *

He stopped. Stopped caring about anything. He relived the same day for the… what was it? He lost the count after thirty six. And yet Dad never gives up.  
He just wants for it to stop one way or another. And he know Dad want that too.  
It began with his wake up to this stupid music. Then Sans come into his room excited for the new day and force him to go out from bed.  
Then it's breakfast, with tacos. He stole a bottle of honey, to help him with the day.  
Then there is the alarm. His Dad come and tells them to stay inside the house. Sans disobey, knowing he will never be scolded for that. He follows.  
They find the Human, they fight and Sans is hurt. He dies and he kill the human with the Blasters. Dad come, use his device and he wake up again, and again, and again and again…  
They tried everything. Locking the door, distract his brother, go away in another place… He even knock him out once but he dusted anyway. He was too strong for his brother.  
He hated his father for that. It was because of his parenting if his brother think he can capture a human alone! He won't listen to reason, because he's the Magnificent Sans, Royal guard in training and soon to be knight.

* * *

It's over. This time; he did it. But at what cost?  
He looks at his brother's sleeping form on the couch. He never seen his sibling so tired before. And yet, he didn't have any memories.  
So he goes to his room, leaving his brother get his sleep. Once alone, he shakes and cry. He can't do that in front of Sans. He stopped caring so why does it hurt so much?  
He remembers everything. Finding the human first, sending him in the wrong direction. And Dad…  
He could still hear the skull cracking, the explosion of the machine and… Nothing. Gerson couldn't remember. He was alone, more alone than ever.  
He's scared to sleep. He takes the first paper he found, an old drawing, even on it, his father's face was fading. He takes a large red pencil and writes: Never Forget.

* * *

 _I didn't have many idea for this AU. For me it's one of the weakest one if we don't take liberties with the characters._  
 _I like it anyway. It just need to focus less on Sans and Pap. (I know it's ironic after reading the story but I'm searching for more depth in this AU)_  
 _Thanks for reading, it's been nice to write in english for once._  
 _And if you have an AU you'd want me to write about in this Fatherhood serie, don't be shy and ask me, it can led to some interesting stories._


	4. Alone

_**Undertale was created by Tobyfox. This guy is a genius and i only use his characters**_

 _New tags and new characters! Gaster is not the only father figure ;)_  
 _I dedicate this chapter to Omoni._

* * *

As long as she remembered it, she'd always been alone. Swimming in this dark and infinite nothingness. There were only a few things she was sure of. There was the bottom,scary and full of fish. A place where it was eat or be eaten. And there was the top. No one went, the fish that disappeared never returned. It was scary.

Sometimes she would encounter one like her but it always ended in a fight. The Lake, as some called it, was too small for all the Deep Ones. They're loners, that's the only thing she's learned. Then she remains alone.

Her fins change slowly into arms and legs. She becomes curious. What's up there? Why do the fish leave and not come back?

So she swims. She reaches the top and approaches her hand. His hand passes through the top. Strange.

She approaches her face, she wants to see. There is still a high above the top. A higher top! And there are small lights. Sharp and blue shapes that shine. This top is empty, there is not the familiar presence around it.

She is afraid, she plunges to the lowest. She was too big to be eaten now.

One day she becomes curious again. If there is a higher than she believed, what is beyond?

She goes up, pulls out her face. She looks at the light before being attracted by a form not far away. There is a strange form, like a seaweed but of the same color as her skin. She approaches and then finds a rock. She tries to swim around it but there is nothing to swim in. This rock is like the bottom, the bottom of the lake. She puts a hand on it, it's weird not to swim.

Then she tries to get out of the lake, to leave the full, her home. This is the first time she really stands, it's difficult and her legs hurt. She falls.

But she wants to see what this seaweed is. She wants to discover.

She uses her hands, then her knees to help, she hurts but she does not give up. She never gives up, she is a Deep One.

Finally she arrives at the blue seaweed, it shines a little now that she is near. She decides to touch it, suspicious, ready to return to familiar full.

She touches the seaweed, it's soft. And for the first time, she distinctly hears:

"Hey! Wait for me Megane! "

She jumps. She had never heard so clearly. She likes this sound, it is pretty. She loves that voice.

Then she hears another, it is not the same.

"What are you doing here?"

She looks up, surprised. In front of her is a creature, a tortoise. She heard about it in the full. He wears strange things over his skin, he is immense. She is scared.

"Do not be afraid my child. What's your name? "

She understands. Even if the sound of his voice is clearer than when asked in the full.

"U ... Un ..." she begins to answer.

She is surprised. His voice is too clear, too sharp. But she continues.

"Undyne. "

* * *

He loves this little one. She is a real treasure. The Deep Ones are rare, they prefer solitude and hardly ever go to the surface. And they do not raise their children.

Too bad. This little girl is too young to be alone like that. And she's full of curiosity. But she is still a Deep One. The way they grow up at the bottom of the water is tough. Below, only the force is respected. There are not only monsters but also beasts in the waters.

He take her in, he could not leave her alone. She's not more than three years old. She does not live totally with him though, she always wants to return to "the full" as she says. She prefers water, that's normal. But she now keeps the outskirts of the lake as its territory. She has already attacked a few monsters who just passed by.

She explained to him one day with her childish words. In the full, you have to fight, that's how you become strong.

Yet, she always knew when to stop and who not to attack. If she hurt someone, even accidentally, she find a way to heal them after the fight, but not without boasting of his victory first.

He got used to finding her near him without warning. He loves her company. She's a young soul full of kindness despite the appearances.

He watches her grow slowly.

One day, he finds her alone and weeping. She does not like being alone anymore, she said. A child told her she had no friends and that she had to stay with the fish. A child who beat her in battle. He consoled her. But he's just an old turtle. And he can not spend all his time watching a turbulent child. Even if he loves her as if she were his own granddaughter.

He finally understood. She fights to attract attention. To show that she deserves to exist outside of the lake.

She wants to prove that she is worth as much as a surface monster. She is determined.

* * *

He can not believe that such a young girl fought so ferociously. She had not managed to touch him once, of course, but she had great potential. And now she was kneeling in the mud, exhausted. He does not see his face but recognizes the shaking of a crying child.

He looks at her with kindness. He would like to tell her that everything will be okay, to take her in his arms as he would have done with ... But he refuses. He is the King, carrying on his shoulders the hopes and dreams of his people and on his hands an indelible blood. He no longer dares touch a child with his soiled hands . Even when he goes visit the schools, he mostly avoids touching children on his own.

"You're really good, little one. With a little more discipline, you could probably even beat me! "

"Tss ..." She gets up and faces him. He can see in her eyes that she holds back her tears. He feels bad. "I'll never do it. You're too big and too strong. I will never do great things like you. "

He watches her get up and take the way out. Her clothes are full of earth and there are golden petals in her scarlet hair. He feels bad for her. He advances and stands in front of her to block the exit gently, he does not want to frighten her.

"Oh but I know you can. But, for that, you'll have to train with other people. "

He heard her whisper.

"Nobody wants to stay with me ... Except Gerson, but he's too old and too strong. And he don't have time with his store. "

He understands now. This little girl must not be more than eight years old and yet, she is so alone. He refrained from taking her in his arms to comfort her. He can't do that, he's afraid of getting attached and being hurt again.

"You know what? I've got plenty of time. I do not have much to do, you know, I could train you. And I'm confident that you will beat me in battle one day. "

She looks at him with big eyes, astonished. He expected it, his status as king and Boss Monster often takes him away from normal monsters. What's got into him? He must have frightened her.

"That is true? You'd do that? "

He sees hope in the eyes of the child. And he would never want to break the hopes and dreams of a little girl.

"It is a promise. I'll teach you how to beat me. But you have to be patient. It takes time and practice to improve one self. "

She jumps on him, it's not an attack, he does not evade. She gives him a hug. It had been so long that he had not felt this warmth in his heart.

* * *

The training was rough but fruitful. She managed to master her magic better than ever. Since the beginning of the training, she had noticed improvements. She had even been able to kick the buttocks of several children who wanted to bother her in Waterfall.

Sunday had become her favorite day of the week as she spent it training with Asgore. Sometimes she would see him on other days just for the pleasure of seeing him. To do that, she just had to cross the lake where she was born to New Home.

She helped him with the flowers, she listened to him talk about gardening, they drank tea together ... He was the only one who stopped in what he was doing just for her.

She took advantage of it. At least she was no longer alone or stuck with Gerson. She loves this old turtle but is often too busy to spend time with her.

Today, training was particularly tiring. Of course, Asgore, he is not tired. He is the strongest of all monsters and she admires him. But she's tired.

Both sit on the steps of Asgore's house, it's time for the break. She's exhausted.

Without saying a word, she takes a piece of Asgore's cloak and hides underneath before putting her head on her mentor's lap. She's so tired. The cloak of Asgore is like a soft blanket. He says nothing, he looks surprised. She smiles at him and falls asleep.

* * *

He can not believe that a child trusts him to the point of falling asleep on his lap. Especially her. She is the lonely child. He spent a lot of time with this little girl. She became his sunshine, his little happiness that changed his daily life and prevented him from thinking about his cowardice.

She is peaceful when she sleeps. All her energy, all her aggressiveness have disappeared.

She has changed a lot since their first meeting. Though always unreflective, she is more assertive and no longer loses her determination to failures. Her reactions always astonish her, as when she almost set the kitchen on fire just by heating water for tea to, a few minutes later, calmly help him with his garden, paying close attention to the flowers.

And there she slept on his lap, exhausted by training.

He is proud of her and all her efforts.

She knows what he did, he confessed it to her one day when he found her close to the coffins. But she believes in him despite everything and continues to say that it is for the good of the monsters. She believed in his words without a doubt.

She trusts him despite the weight of his sins. He approaches a trembling hand on sleeping child and rubs her back gently as he did long ago, for his son.

She makes him feel things, far long forgotten. He then begins to tell her a story. She sleeps with closed fist. She will not remember this story once awake.

He tells the story of his children and his wife. He tells her about his regrets and fears. And finally, he tells her how a little girl helped him. A little girl whom he considers his own child and whom he hopes to see grow to be a magnificent woman one day.

* * *

 _I had a inspiration rush tonight. I draw a picture and made a new oneshot! All on the same theme._  
 _I love the relation between Undyne and Asgore, It really was obvious to me that they had a Father/daughter relationship._  
 _There is not enough fanfictions or art about that._

 _A big, big big thank to Omoni helped me by correcting this chapter!_


	5. LOYALTY

It was him, the cause of all of it, everybody said it. He had created the Law which threatened them all. Even if her specie was naturally attacked each other already, she had suffered from solitude since his birth. Normally, only the youngs in their embryonic state would die in mass due to fishes and to other predators present in waters of the lake. But far from the Royal Guard, supposed to enforce the limitations, the Deep Ones attacked their youngs instead of the predators to gain faster LV. At least ,with the predators, there was always at least one or two survivors on around thirty soul created. But the adults were merciless. The parents never attack their eggs but the others never go without it. Her people risked to disappear for a stupid story of pride and loyalty to King. She had been lucky to escape the thirst of dust of the adults when she was that a small larva, and had taken refuge outside the lake as soon as her legs had stops growing. She was only three years old, she was quite small and lost. The Deep Ones almost never went out of the lake. She was alone. And she had seen her brothers and sisters be massacred one after the other in a more or less cruel way. An old tortoise found her very fast. She was starved after several days not daring to return to the water to find some fish. She was certain to have seen the scales of one of her kind sparkling not far, waiting that she returns to get points of execution easily. When the tortoise saw in which state she was, he took her to his home. He feeds her, dressed her with a striped shirt and explained her why the Undergroud was like this. The adults had really become crazy. Gerson told her about a peaceful time, not so long ago, when kindness was what monster soul was made of. Then he told her the madness of King and how the inhabitants of the Underground were obliged to kill each other. How all these wills to survive, this slaughter, had created some Determination to monsters, changing slowly their appearance and making them lose their sanity. This stories seem like a dream, to her who was only a child. Monsters had formerly a dominant color in their souls each, which was sawn through their eyes. But she had met until now only monsters with the blood red eyes: the color of the Determination. Gerson said it's toxic. And the first time she looked in a mirror, she noticed that her eyes were as scarlet as her hair. She made then a decision. She wanted to change things. And if the one responsible was the King, then she would take care of the problem.

* * *

The night was very quiet. The artificial lights of the Underground emit a weak brilliance, creating a similar atmosphere of the nights of the surface. The silence reigned in New Home. The city seemed deserted of life. The air suffocating with dust and Determination seemed denser, something was coming. Asgore was persuaded. He waited for this moment since almost fifteen years. Lengthened on his bed, ears on the watch, he watched for the signs of an attack, faking sleep. After what seemed to be hours, he eventually hears steps felted in his room. It was not what he expected. A light presence soared by his side on the bed and he heard the ringing of metal. A murderer! Without waiting, hev brought out his big hand from the blankets and caught the arm holding the blade which threatened him. He did not want to die from the hand of a single soul! He expected a rebellion of the people, not the action of a solitary person! And if it was necessary to give other examples of its cruelty, he would make it. The murderer was particularly light. No heavier than Froggit. It was surprising because the smallest monsters had mainly run away after he created the wanted to see the face of his aggressor. In one second, he summoned his trident which shone of threatening blood red magic and pointed it towards his opponent. " No! " He stopped in some millimeter of the throat of his aggressor and looked at them, trying not to let appear his surprise. It was not a small monster, it was not even an adult. Between his claws struggled a girl, a Deep One child who had to be no more than seven or eight years old. She looked at him with hatred and tried to release herself from his grip by scratching the hand, no more intimidated than that by the point of the trident on her throat. He knew he insisted to spare childrens from the Law, so that they remain protected from his madness. And nevertheless her was there, uncertain, in front of a child which had come murder him. Which had manages to penetrate into his house under the nose of the guards. " How did you enter and who sends you, girl? " He grumbled between his teeth. He did not want to alert the guards for a child. She continued to fix him in the eyes, trying to be intimidating in despite the shivers shaking her little body. " Through the window. You are stupid to left it open. " She answered with provocation. " And who send you? Answers! What rebels would have sent a child to try to kill? Who? " He squeezed the arm of the girl with force, ready to break the bones. He had to keep appearances. " Myself. " The answer took him by surprise. She had to lie. It was impossible that a girl has the idea to come to murder him. " Liar! " He crashed his trident in the wall, sticking the throat of the child between the teeth of his weapon. The wall of a spotless white covered itself with profound cracks. The child lost her distrustful air, finally showing her fear. He was going to make her speak. It was only a question of time.

* * *

All her body made her suffer. She didn't know her body could hurt so bad. She was only telling the truth. Her will to kill was hers, and no one else. She had told in detail her life and how she had prepared her murder for weeks before acting. She had told them at least ten times. They had eventually believed it. But at which price. She had begged them to finish her, but King had insisted on keeping her alive. She ignored why. She wanted just to die at this moment. The grating of the door made her shiver. She did not want to get more pain! She had told everything them! Everything! But in place of pain, she felt the heat of healing magic traveling her bruised body. Surprised she looked who had entered and was surprised seeing King tilted on her, his big claws hands glittering with a powerful green magic. She thought she saw regret in his eyes but they hardened when he saw her gaze on him. She said nothing, neither does he, the pain began to dissipate. She contracted her muscles, ready to defend herself if it was only a trap to hurt her again. After a long silence, she heard the deep voice of King address her. "Even by being more discreet you would not have been able to kill me, you know. You are not rather powerful enough to make me damage, especially with the knife which you had. " She answered nothing. He wanted to humble her. Nothing more. " A lot of power is needed to end a monster Boss like me, you know. The monsters of your sort can become extremely powerful if pushed in the right direction. You hate me with all your soul, I know it. But there is a big potential in you. You are only a child, after all. Normally I should leave you here until you are old enough to get out of your stripes to kill you and make you an example. " She was not able to refrain her shivering. Her eyes stared deeply in the King's, supplicant. She did not want to spend the rest of her young life in a cell. " But I am persuaded that you can be useful for the kingdom. But for it, you'll have to learn to be as loyalty as the rest of your people. Tomorrow, you will be rehoused to the palace, under surveillance. I'll train you personally and shall teach you to overcome even the most powerful monsters . Even I. Any disloyalty, any fault from you will be severely sanctioned. " She looked at him with incomprehension. She did not have pain any more and suggested to teach her how to fight? After she had tried to kill him? She swore herself, in the depths of her, that she shall not hesitate one second. From the moment when she would be in capacity of doing it, she would kill old monster King.

* * *

For the first time since he had taken her under his wing, he was finally going to let her go by herself. After years of training, having taught her the rudiments of fight, he was going to test her loyalty. He did not show but he had become attached to this small ball of energy that was Undyne. She was a difficult child but he had, in time, learnt how to manage her without hurting her. He had let the rumors circulate saying that he kept a girl a prisoner and saying that he taught to her to kill for him. And he had finally heard rumors of a rebellion against him. If he continued in the right direction, the people would lift up themselves, he would be dethroned, doubtless killed. He would not have to carry the people's hopes and dreams on his shoulders anymore. And he would have what he deserves. He was anxious to let Undyne leave without escort. But whatever happens at the moment, he knew that he would see again her. And that he would be proud of her. He sent her kill a member of the rebellion to leave them a message. She would face a choice. End the mission and come back to him, showing her loyalty. Or listen to the rebels, join them, why not take their head and guide the people one day against him. In this case he would see again her when finally she would kill him. And he will be so proud of her. She had the material of a queen. Before she leave, dressed in a light armor and armed only with her magic, he gave her a last piece of advice. "Don't die, it is an order. And come back."

* * *

Kneeling in front of her king, she felt full of pride. She had succeeds. She had the power to overcome any monster. Even him. But she would never hurt him. He had taken her away from the danger by raising her. He trained, educated and protected her since childhood. He gave her the key to survive in this kill or be killed world. She could never thank him enough. All her life turned around the monster King. She killed for him since her adolescence and now that she was an adult, she dedicated him an undying loyalty. She was ready for anything for him. The day before, during their last training, she finally touched Asgore for the first time, leaving an ugly scar on his eye. Never she had seen her mentor so proud. And now, on this day, she had decided to make a gesture to prove him her eternal loyalty. She did not see the face, keeping the head lowered. But she imagined him looking at her with all the imposing presence of an emperor. He was the monster which had raised her. She knew him well. " Fifteen years ago I tried to kill you. Nevertheless, rather than to avenge you and to condemn me, you gave me a life which I would never been able to dream. Forgive me, my King. Father... I hurt you. Let me be equal with you. " She took a big breath, she knew that she was going to be in pain. But the pain did not frighten her any more. She had known worse, she would survive. She raised her right hand to touch her own face and crashed her clawed fingers in her left eye. She hold with great difficulty a cry of pain before tearing away her eye and presenting it to the King. " An eye for an eye... I belong to you. And I promises to never let anyone get to you. I am your loyal assassin. "

* * *

 **5th Oneshot of the Serie.**  
 **I did not corrected it by my friend so if you see a mistake don't hesitate to tell me, i'll correct it.**  
 **English is not my native language.**

 **I like to think of Underfell Undyne as an assassin and not the Captain of the royal guard or Second in command.**


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